These studies represent a small independent add-on to two NIH funded investigations into brain structure in psychosis. We wished to explore whether patients with hallucinations and delusions in diverse neuropsychiatric disorders, including schizophrenia, manic depressive illness, and Alzheimer's disease, show abnormalities of common anatomical substrates compared to age-matched controls. In particular, we hypothesized that disease involvement of temporal limbic and neocortical regions would predispose to psychosis. We found that a disproportionate involvement of mesiel temporal regions and posterior superior temporal gyrus, especially on the left side, appeared to be a common mechanism across psychotic states.